1. Field of the Invention
The present invention is directed to the field of spray adjuvants. More specifically, the present invention is directed to a spray adjuvant comprising both a fertilizer and drift reducing agent.
2. Description of Related Art
Agrochemicals, such as herbicides, insecticides, fungicides and other crop protection chemicals frequently require the presence of adjuvants to achieve maximum, or even acceptable, performance. The term “adjuvant” includes any ingredient added to an agrochemical to aid or modify the action of the agrochemical, or to alter the physical characteristics of an agrochemical spray composition, including, but not limited to, formulation aids. Generally, the agrochemical, adjuvants and water are mixed in a tank to form an agrochemical spray composition, which is sprayed onto a target area, such as a field.
There are many types of adjuvants. Drift reducing agents are adjuvants that modify the drift and deposition characteristics of the agrochemical spray composition. Drift, a longtime problem with agrochemical spray compositions, is a function of water droplet size. As a result of drift, the agrochemical spray composition is carried away from its intended target, resulting in wasted product, unintended treatment of border crops that may be damaged by the composition and potential air, ground and water pollution. It is generally agreed that droplets with diameters of 100 microns or less are most susceptible to drifting off target. Droplets with diameters over 100 microns are more likely to produce even spray patterns that uniformly cover the target area, with little drift. Most drift reducing agents generally increase the viscosity of the agrochemical spray composition, which increases droplet size, decreases drift and increases deposition of the agrochemical spray composition on the target. However, if the viscosity is too high, the agrochemical spray composition will not be applied evenly. Rather, the spray pattern will comprise streaks of heavy and light application within the target area, which can damage the over-sprayed plants and reduce insect or weed control in the under-sprayed areas.
Known drift reducing agents include natural gums, such as guar gum and its derivatives, and synthetic polymers, such as polyacrylamide, polyethylene oxide and polyvinylpyrrolidones. Synthetic polymers may be supplied to the end user in an organic carrier solvent for addition to the agrochemical spray composition in the tank. Use of the organic solvent can limit the dispersibility of the polymer and requires the end user to deal with the potential problems associated with a volatile organic compound. Other synthetic polymers are provided in a dry flowable form. The dry flowable polymers must swell upon mixing in the tank to increase the viscosity of the agrochemical spray composition. Such dry flowable polymers often cause nozzle and/or filter clogging during application and are generally recognized to produce an adverse spray pattern uniformity that increases the likelihood of inconsistent pesticide coverage.
Other types of adjuvants are anti-foam and de-foaming agents. In many agrochemical spray composition, substantial foaming occurs in the spray tank during mixing and application of the composition. For example, the herbicide glyphosate, sold under the trademark “ROUNDUP ULTRA,” includes surfactants that create foam in the tank mix. It is desirable to include an adjuvant to help prevent the foam from forming or to knock down existing foam. Antifoam agents are adjuvants designed to be added to the tank mix to prevent foam in the spray tank, whereas de-foaming agents are adjuvants designed to knockdown foam once it has developed in the spray tank. Some antifoam agents provide knockdown ability and can be used for both purposes. When used herein, the term “antifoam agents” generally refers to agents that prevent and/or knockdown foam.
Yet another category of adjuvants are activator adjuvants, which enhance the biological performance of the agrochemical spray composition. Activation adjuvants include water-soluble nitrogen-based fertilizers, such as ammonium sulfate. Ammonium-containing fertilizers reduce the pH of the agrochemical spray composition, improving uptake on certain weed species.
Ammonium-containing fertilizers, in particular ammonium sulfates, are particularly useful in enhancing herbicide efficacy. The sulfate portion released by ammonium sulfate “conditions” the water of the agrochemical spray composition by binding hard water minerals such as calcium, sodium, iron and magnesium and thereby preventing such minerals from antagonizing the herbicide. This is particularly true when used with glyphosate herbicides or other weak acid herbicides. It is believed that the ammonium ion enhances glyphosate performance by binding with the glyphosate to form a more soluble, readily absorbed glyphosate-ammonium complexes. Glyphosate-sodium and glyphosate-calcium complexes are less soluble and therefore not as readily absorbed. The sulfate ions released by the ammonium sulfate precipitate the sodium and other hard water minerals, leaving the glyphosate molecules free to bond with the ammonium ions. Larger amounts of ammonium sulfate are required when harder water sources are used in the agrochemical spray composition of certain herbicides. Additionally, ammonium-containing fertilizers increase the absorption of agrochemicals into target plants by stimulating growth of the plant, and aiding uptake into the phloem so that the agrochemicals can be translocated.
Fertilizer grade ammonium sulfate is generally comprised of large particles that are difficult to dissolve in agrochemical spray compositions and may contain insoluble impurities that can damage spray equipment and clog spray nozzles. As a result, ammonium sulfate is often processed before it can be used as an adjuvant in agrochemical spray compositions. Dry ammonium sulfate can be screened to a smaller particle size that will disperse more quickly when mixed in the spray tank. During the screening and handling process, the material is screened for impurities. Alternatively, the ammonium sulfate may be pre-solubilized in water and packaged into liquid containers, during which process it is filtered to remove impurities. However, because the holding capacity of water is limited, in order to achieve the high rates of ammonium sulfate often needed, an unacceptably large amount of product is required, and end-users must dispose of the bulky liquid containers.
If end-users wish to use multiple adjuvants, they are required to measure the appropriate amounts of the individual adjuvants, agrochemical and water, and mix the components in the tank to form the agrochemical spray composition. The end-user must ensure that the amount of the components are correct, the materials are compatible and properly dispersed, and proper safety precautions are followed. Because this can be a complicated and time consuming task, there is a need for adjuvant products that combine two or more adjuvants to simplify preparation of the agrochemical spray composition.
One known method for providing a combination adjuvant involves dry blending two types of adjuvants, such as a fertilizer and a dry drift reducing agent. However, because the fertilizer particles are generally larger than those of the drift reducing agent, the particles separate during shipment, such that the mixture does not have a uniform composition. To assure the separate components stay mixed, it is known to grind the two materials to similar sizes, so that they will not segregate during shipping and handling. However, grinding to a small particle size results in a fine-dusty end product that is difficult for the end-user to use. Further, finely ground dry drift reducing agents take considerable time to hydrate and achieve the desired viscosity. When the drift reducing agent does not hydrate quickly enough, it can agglomerate and plug screens and nozzles during application.
Ammonium sulfate is commonly used as an activator adjuvant to enhance the performance of herbicides, particularly glyphosate. Commercial brands of glyphosate, such as that sold under the name “ROUNDUP,” recommend varying rates at which the ammonium sulfate should be used in association with the product, referred to as “use rates.” Thus, it is desirable for any combined fertilizer and drift reducing product to be useful over the entire range of the recommended ammonium sulfate use rates. However, as more ammonium sulfate is added to the agrochemical spray composition, more drift reducing agent is added. As a result, when large amounts of fertilizer are added, too much drift reducing agent is added, resulting in a composition with a viscosity that is too high for proper application. If the amount of drift reducing agent in the blend is reduced, it will not provide sufficient drift reduction at low use rates. Thus, when the drift reducing agent is dry blended with the fertilizer, the range of use rates for the blended product is limited.
Thus, a need remains for a single product that supplies two or more types of adjuvants, and can be used over a wide range of use rates, without the problems associated with dry blended adjuvant mixtures.